Safety: Turn off power before opening the control pack or touching heater wiring.

Verify mode and set point: Ensure the spa is in standard mode (not economy/sleep) and the set temperature is above current water temperature.
Check filtration/heating cycles: Some MAAX models only heat during programmed filter cycles. Confirm cycle times in the user menu.
Inspect control settings: Compare dip switch or jumper settings on the control board to the MAAX wiring diagram for your model to ensure correct configuration.
Test heater: With a multimeter, measure resistance of the heater element and confirm it matches MAAX specifications. An open or very high resistance indicates a bad heater.
Check relay operation: When the spa calls for heat, listen for a relay click and measure voltage across the heater terminals (qualified person only). No voltage suggests a control board issue.
Replace failed part: Install a new heater assembly or control board as indicated by testing.

Spa powers on but will not heat; water stays at or near ambient temperature with no heat-related error code.

Possible Causes